Rotary engine oil pump priming arrangement

ABSTRACT

In a rotary engine having front, intermediate and rear housings, front and rear rotor housings, an oil tank secured to the rear housing and an oil pump located at a higher elevation in the front housing, there is provided a longitudinally extending oil suction passage through these housings between the tank and pump having a drain trap in the rear housing that acts to retain oil in the suction passage for pump priming.

United States Patent Stevenson 1 1 Jan. 7, 1975 [54] ROTARY ENGINE OIL PUMP PRIMING 3,618,711 11/1971 Vollmer 418/88 3,659,562 5/1972 Jones H 123/801 ARRANGEMENT Paul D. Stevenson, Ann Arbor, Mich.

General Motors Corporation, Detroit, Mich.

Filed: Feb. 4, 1974 Appl. No.: 439,037

lnventor:

Assignee:

References Cited UNITED STATES PATENTS 8/1956 Stegemann 184/63 Primary Examiner lohn J. Vrablik Attorney, Agent, or FirmRonald L. Phillips [57] ABSTRACT ln a rotary engine having front, intermediate and rear housings, front and rear rotor housings, an oil tank secured to the rear housing and an oil pump located at a higher elevation in the front housing, there is provided a longitudinally extending oil suction passage through these housings between the tank and pump having a drain trap in the rear housing that acts to retain oil in the suction passage for pump priming.

2 Claims, 3 Drawing Figures ROTARY ENGINE OIL PUMP PRIMING ARRANGEMENT This invention relates to a rotary engine pump priming arrangement and more particularly to such an ar' rangement for a rotary engine wherein the oil reservoir and the oil pump which is at a higher elevation are very remote from each other.

It has been found desirable in rotary engines wherein rotors can be added in line to increase engine size to have an oil tank secured to the engines rear housing supplying a gear type oil pump that is located in the engines front housing at a higher elevation. Insuch an arrangement it has also been found desirable to have a suction passage which extends longitudinally through the engines housing to connect the tank and pump. Because this oil suction passage is very long and would normally drain to the oil tank when the pump is not running, the pump may suck too much air on start-up so that the pump gears do not retain the necessary wetness to effect adequate priming to establish normal oil pumping operation.

'An object of the present invention is to provide a new and improved rotary engine oil pump priming arrangement.

Another object is to provide in a rotary engine an oil pump priming arrangement having an oil tank at one end and an oil pump located at a higher elevation at the other end, and an oil suction passage through the engine connecting the tank and oil pump having a darn immediately upstream of the oil tank that traps oil in the suction passage for pump priming.

These and other objects of the present invention will be more apparent from the following description and drawing in which:

FIG. 1 is a longitudinal view with parts in section of a rotary engine having an oil pump priming arrangement according to the present invention.

FIG. 2 is an enlarged partial view taken along the line 2-2 in FIG. 1.

FIG. 3 is a view taken along the line 33 in FIG. 2.

Referring to FIG. 1 there is shown a two-rotor rotary engine 10 having an oil pump priming arrangement according to the present invention. The engine 10 has an outer body comprising a front housing 14, a rear housing 16, a front rotor housing 17, a rear rotor housing 18 and an intermediate housing 19 between the two rotor housings 17 and 18, all clamped together by bolts 20. The engine housing encloses a pair of chambers 22 and 23 that are defined respectively by inwardly facing peripheral walls 24 and 26 of rotor housings l7 and 18 and opposed, spaced parallel end walls 28, 30 and 32, 34 of front housing 14 and intermediate housing 19 and the latter housing and rear housing 16. Each of the peripheral walls 24 and 26 is in the shape of a two-lobe epitrochoid or curve parallel thereto. A crankshaft 42 extends through the chambers 22 and 23 and is rotatably supported in main sleeve bearings 44 and 45 which are fixed in stationary gears 46 and 47 that are bolted to the respective housings 14 and 16 as shown in FIG. 1, the crankshafts axis being coincident with the centerline of the peripheral walls 24 and 26.

The crankshaft 42 is provided in the housing chambers 22 and 23 with eccentrics 50 and 52 on which hollow rotors 54 and 56 having sleeve bearings 57 and 58 are mounted for rotation about the eccentric centerlines, these centerlines being located 180 apart and spaced equal distances from the crankshaft axis. The rotors 54 and 56 have the same general shape of a triangle having respectively three faces 61 and 62 which are convex and face the peripheral walls 24 and 26 and cooperate therewith and with the end walls 28, 30 and 32, 34 to define three variable volume working chambers 67 and 68 that are spaced about the rotors and move with the rotors within the engine housing.

A fixed cyclic relation between each of the rotors and the crankshaft is obtained by gearing between each of the rotors and the housing. Referring to rotor 54, there is the stationary gear 46 which is fixed to the housing and is received about and is concentric with the crankshaft 42. The gear 46 meshes with an internal tooth gear 71 that is concentric with and formed on the outboard side of rotor 54. The gear 71 has one and onehalf times the number of teeth as the gear 46 with result that this gearing enforces a fixed cyclic relation such that the crankshaft makes three complete revolutions for every one complete revolution of the rotor. Similarly, the other stationary gear 47 meshes with an inter nal tooth gear 73 on the other rotor 56 with their mesh at a location diametrically opposite that of gears 46 and 71. Thus, the chambers 67 and 68 move with the respective rotors 54 and 56 as they revolve about their axes while also revolving about the crankshaft axis with each chamber twice undergoing expansion and con traction during each rotor revolution.

Sealing of the working chambers such as the working chambers 67 is effected by three apex seals 74 each of which extends the width of the rotor and is mounted in an axially extending slot at one of the rotor apexes, six corner seals 75 each of which is mounted in a hole in one of the rotor sides near one of the rotor apexes, and twelve side seals 76 each of which is mounted in an arcuate groove in one of the rotor sides with these seals arranged in pairs and extending adjacent one of the rotor faces between two .of the corner seals with the corner seals each providing a sealing link between one apex seal and the adjacent ends of two pairs of side seals. The apex seals 74 are each spring biased radially outward to continuously engage the peripheral wall 24 and both the corner seals 75 and the side seals 76 in both rotor sides are spring biased axially outward to continuously engage the respective end walls 28 and 30. In addition, there is mounted in grooves in each rotor side inward of the side seals 76 a pair of spring biased circular oil seals 82 which are concentric with the rotor and sealingly engage the opposite end wall to prevent oil from reaching further outward. The rotor 56 carries a similar gas and oil seal arrangement.

A combustible air-fuel mixture is delivered by an induction system, not shown, that includes a carburetor that is mounted on an intake manifold. The intake manifold is connected to the engine housing and has branches that communicate in the engine housing with intake ports in the housing end walls. Upon rotor rotation the combustible air-fuel mixture is sequentially, periodically admitted to the chambers 67 and 68 as they are expanding by the traversing motion of the rotor sides relative to the respective intake ports whereafter the chambers then close to their intake ports and contract to compress the thus trapped airfuel mixture in readiness for ignition. Combustion by spark ignition is provided by a suitable ignition system, not shown, which applies voltage at the proper time to pairs of spark plugs which are mounted on the rotor housings with their electrodes open to the combustion chambers through the respective peripheral walls. For example, the electrodes of the two spark plugs mounted on rotor housing 17 are open to the chambers 67 through the interior peripheral wall 24 and are peripherally spaced there-about so that one plug leads the other plug relative to rotor rotation. In such an arrangement both plugs are fired at the same time or different times or only one plug is fired according to certain engine operating conditions as is well known. With combustion the peripheral wall takes the reaction to force the rotor to continue rotating and eventually each working chamber following the power phase is exhausted during the exhaust phase by an exhaust port, not shown, in the peripheral wall 24 that is periodically traversed by the rotor apexes and is open to an exhaust manifold secured to the exterior of the engine housing. The engine structure thus far described is of conventional type and for a more detailed understanding thereof reference may be made to US Pat. Nos. 2,988,065 and 3,077,867.

Describing now the engines lubrication system so far as it is believed will aid in understanding the pump priming arrangement according tothe present invention whose details will be described in detail later, the engines oil is stored in an oil tank 90 of sheet metal construction which is bolted to the underside of the engine and extends rearwardly of the rear housing 16 as shown in FIG. 1. The oil in the oil tank 90 is delivered under pressure to lubricate and cool the engine by an oil pump 92 of the internal-external gear type which is mounted in the front housing 14 and is located about and driven by the crankshaft 42. The engine is normally angled in the vehicle installation as shown in FIG. 1, and thus the oil tank 90 is in a good position to have oil drain thereto when one or more rotors are added to increase the engine size since such rotors would be added forward of the present front rotor housing 17 and behind the front housing 14 where the pump 92 is mounted, such strategic location of the oil tank being disclosed in copending U.S. Pat. application Ser. No. 460,927 filed Apr. 15, I974 and assigned to the assignee of this invention. Oil is drawn from the oil tank 90 through a screen assembly 94 in the tank and then a suction pipe 96 that extends through a sealed aperture in the roof of the tank as shown in FIG. 1. The suc-' tion pipe 96 extends upward with a close fit into a suction hole 98 bored up through the bottom of the rear housing 16, there being provided an O-ring 100 mounted in the annular groove in the bore 98 to provide a seal between the suction pipe 96 and the rear housing as shown in FIG. 3. Oil being drawn through the suction pipe 96 thereafter passes through a longitudinal extending suction passage 99 that extends forwardly from the rear housing 16 through the rear rotor housing 18, the intermediate housing 19, the front rotor housing 17 and into the front housing 14 where the oil pump 92 is located, this passageway being formed by cored passages in the respective housings that align with each other on housing assembly. The oil pump 92 delivers the oil under pressure to an external cooler, not shown, from which the oil is then directed back to the rear housing 16 where it then may be directed through an oil filter prior to delivery to a gallery tube 101 which passes through a passage in the rotor housings l7 and 18 and intermediate housing 19. The tube 101 joins at its opposite ends in the front and rear housings 14 and 16 with long drilled holes 102 and 103, respectively, that run from the gallery toward the center of the housings and stationary gears 46 and 47. Oil is forced into the crankshaft 42 at each end through restrictive holes 104 and 105 in the front and rear stationary gears 46 and 47, holes 106 and 108 in the front and rear main bearings 44 and 45 and holes 110 and 112 in the crankshaft to a long axial feed hole 113 in the crankshaft that is drilled from the rear end thereof and is plugged by a press-fitted ball 116. Thus, the main bearings 44 and 45 are fed with oil for lubrication, and in addition, holes 118 and 120. connect the axial feed passage 113 to feed oil to the respective rotor bearings 57 and 58. In addition, pairs of orifices 121 and 122 connected to the axial feed passages 113 on opposite sides of the eccentrics 50 and 52 direct oil radially outwardly to the interior of the respective rotors 54 and 56 to effect their cooling and also to lubricate the phase gears 46, 71 and 47, 73. The rotors each have an internal web 126 with holes 128 to provide for circulation therethrough in an axial direction with the oil then exiting outwardly of the rotor and into cavities 130 and 132 in the front housing 14 and the intermediate housing 19, respectively, in the case of the front rotor 54 and into the intermediate cavity 132 and a cavity 134 in the rear housing 16 in the case of rear rotor 56.

The oil after leaving the main bearings, rotor bearings, phase gears and drain cavities, falls to a longitudinally extending drain passage, not shown, that extends through the housings to exit through a drain hole in the rear housing into the oil tank, such provision for oil drainage being disclosed in detail in copending US. application Ser. No 460,928 filed Apr. 15, 1974 and assigned to the assignee of this invention, this disclosure also describing how the oil tank 90 may be internally vented.

Describing now the details of the priming arrangement that will effect adequate priming of the oil pump 92 to establish oil pumping operation, it will be observed in FIG. 1 that with the pump stopped, oil wants to drain from the inclined suction passage 99 back through the suction pipe 96 into the oil tank 90 with the result that on pump start-up, it would need to suck a large volume of air, i .e., a volume equivalent to that of the oil suction passage, before oil from the oil tank would start'entering the pump suction chamber. In the meantime, if the pump gears lose their wetness, the pumping efficiency will drop off substantially with the result that the pump may not prime. To avoid such an occurrence, there is provided a dam 136 in the cored portion of the suction passage 99 in the rear housing 16. The dam 136 is located as close as possible to the oil supply in the tank 90 extending on its right-hand side up from the suction hole 98 and then extending on its left-hand side down to the bottom of the suction passage 99. In the rear housing 16 the suction passage 99 is provided with a flow section 137 downstream of the dam 136 and a flow section 138 at the crest 139 of the dam and upstream of the dam between two of the housing bolts 20 to provide adequate flow area for normal pump suction as shown in FIGS. 2 and 3. The crest 139 of the dam is determined to extend above the normal height of the suction passage 99 in the rear housing 16 and relative to the elevation of the suction passage in the front housing 14 so that with the pump shut down, oil is retained at the level 142 in FIG. 1. At this level, the oil completely fills the flow area of the oilsuction passage 99 in the rear housing 16 and also in the rear rotor housing 18 and extends at a substantial height throughout the longitudinal portion of the suction passage up into the front housing 14.

With the provision of the dam 136 which traps the oil at the level 142 rather than letting the oil suction passage freely drain to the oil tank 90 and on pump startup, the pump will first suck the small volume of air that exists between the pump suction chamber and the height 142 of the trapped oil in the suction passage 99 and will then draw the volume of oil that has been trapped by the dam 136. Thereafter, the pump will suck the relatively small volume of air in the suction pipe 96 that is downstream of the dam 136 and above the normal level 144 of oil in the oil tank whereafter a continuous volume of oil will then be drawn by the pump from the oil tank. Thus, the pump on start-up draws two small volumes of air and an intermediate large volume of oil because of the provision of the dam 136 rather than having to draw one very large volume of air before oil can arrive at the pump. Thus, the dam 136 assures that the pump gears will remain wet to effect adequate priming to establish normal oi] pumping operation.

The above described embodiment is illustrative of the invention which may be modified within the scope of the appended claims.

I claim:

1. A rotary engine comprising a multipart housing including a front housing, a rear housing, a rotor housing intermediate said front and rear housings, a crankshaft rotatably supported in said multipart housing, said crankshaft having an eccentric located in said rotor housing, an oil-tank secured to said multipart housing underneath said rear housing, an oil pump mounted in said front housing in an elevated location relative to said oil tank and driven by said crankshaft, an oil suction passage extending longitudinally through said multipart housing connected at an inlet end in said rear housing to said oil tank and connected at an outlet end in said front housing to said oil pump, said oil suction passage in a normal attitude inclined to drain oil to said oil tank, and dam means in said oil suction passage in said rear housing immediately upstream of said oil tank for trapping oil in said oil suction passage to a height sufficient to reach the ceiling of said oil suction passage so that a volume of oil sufficient to prime said oil pump is trapped in said oil suction passage.

2. A rotary engine comprising a multipart housing including a front housing, a rear housing, a rotor housing intermediate said front and rear housings, a crankshaft rotatably supported in said multipart housing, said crankshaft having an eccentric located in said rotor housing, an oil tank secured to said multipart housing underneath said rear housing, an oil pump mounted in said front housing in an elevated location relative to said oil tank and driven by said crankshaft, an oil suction passage extending longitudinally through said multipart housing connected at an inlet end in said rear housing to said oil tank and connected at an outlet end in said front housing to said oil pump, said oil suction passage in a normal attitude inclined to drain oil to said oil tank, and dam means in said oil suction passage in said rear housing immediately upstream of said oil tank having a crest determined to trap oil in said oil suction passage to a height sufficient to reach the ceiling ofsaid oil suction passage along a substantial length thereof in the direction of said oil pump so that on pump start-up said oil pump draws a small volume of air and then a large volume of oil from the trapped supply followed by another small volume of air and eventually oil from said oil tank. 

1. A rotary engine comprising a multipart housing including a front housing, a rear housing, a rotor housing intermediate said front and rear housings, a crankshaft rotatably supported in said multipart housing, said crankshaft having an eccentric located in said rotor housing, an oil tank secured to said multipart housing underneath said rear housing, an oil pump mounted in said front housing in an elevated location relative to said oil tank and driven by said crankshaft, an oil suction passage extending longitudinally through said multipart housing connected at an inlet end in said rear housing to said oil tank and connected at an outlet end in said front housing to said oil pump, said oil suction passage in a normal attitude inclined to drain oil to said oil tank, and dam means in said oil suction passage in said rear housing immediately upstream of said oil tank for trapping oil in said oil suction passage to a height sufficient to reach the ceiling of said oil suction passage so that a volume of oil sufficient to prime said oil pump is trapped in said oil suction passage.
 2. A rotary engine comprising a multipart housing including a front housing, a rear housing, a rotor housing intermediate said front and rear housings, a crankshaft rotatably supported in said multipart housing, said crankshaft having an eccentric located in said rotor housing, an oil tank secured to said multipart housing underneath said rear housing, an oil pump mounted in said front housing in an elevated location relative to said oil tank and driven by said crankshaft, an oil suction passage extending longitudinally through said multipart housing connected at an inlet end in said rear housing to said oil tank and connected at an outlet end in said front housing to said oil pump, said oil suction passage in a normal attitude inclined to drain oil to said oil tank, and dam means in said oil suction passage in said rear housing immediately upstream of said oil tank having a crest determined to trap oil in said oil suction passage to a height sufficient to reach the ceiling of said oil suction passage along a substantial length thereof in the direction of said oil pump so that on pump start-up said oil pump draws a small volume of air and then a large volume of oil from the trapped supply followed by another small volume of air and eventually oil from said oil tank. 